Apple does not directly control the pricing for third-party apps and the company did not immediately respond to CNBC's request for comment. But the developers' move to adjust the rate could be a limited time offer in response to the coming birthday of Apple's App Store, according to The Verge, which was the first to report on the slew of apps changing their price.

Considering more than $10 billion has been shelled out to developers of the 850,000 apps that have been available on Apple's App Store in the past five years, it's kind of a no brainer that developers may want to do something to thank iOS users, but some of the sales also may have been a part of Fourth of July specials.

In May, Apple said customers are downloading more than 800 apps per second, which translates to about 2 billion apps per month. However, while Apple's App Store still generates the majority of app revenue, Google's Play Store is gaining share, according to the app analytics firm Distimo.